Dye-sensitized solar cells are a promising energy source due to their potential low-cost. Current research on dye-sensitized solar cells is focused on new methods and materials to improve their energy conversion efficiency, life cycle, and cost. Titania (“titanium dioxide,” TiO2) is an n-type wide bandgap semiconductor that absorbs photons in the ultraviolet energy region. As such, in typical dye-sensitized solar cells, dye molecules are adsorbed on a titania layer to allow for photoelectric conversion over a broader spectral range. When sunlight radiates onto the DSSCs, electrons in the highest occupied molecular orbital (“HOMO”) in the dye molecules absorb photons from the sunlight and jump to the lowest unoccupied molecular orbital (“LUMO”). The electrons in the LUMO are then injected into and pass through the titania layer to a transparent conductive oxide coated on a substrate and then to a load to provide electricity. The newly vacant HOMO is supplied with electrons from iodide ions (I−) when iodide is oxidized to triiodide (I3−). Meanwhile, a platinum counter electrode acts as catalyst to reduce the triiodide back to iodide.
Titania particles having higher surface areas in the titania layer allow for the adsorption of a larger number of dye molecules needed for light-harvesting, thereby improving the efficiency of dye-sensitized solar cells. In addition, better intramolecular connections between the titania particles and better adhesion of the titania particles to the transparent conductive oxide diminish reactions between the photogenerated electrons and the triiodide to improve the electrical conductivity in the dye-sensitized solar cells. Therefore, to improve the efficiency and lower the cost of dye-sensitized solar cells, a new, more economical method of preparing titania pastes including improved morphologies of titania nanoparticles for use in dye-sensitized solar cells is needed.